1. Field of the Invention
The present invention is related generally to rotary vane pump assemblies.
2. Related Art
In general, rotary vane pump assemblies are positive displacement pumps that include one or more vanes that are mounted to a rotor which is rotatable within a cavity, or an inner chamber, of a housing. A pressure differential is applied across the vane, which causes the rotor to rotate within the open chamber of the housing. The rotor is coupled with an output shaft which may be attached to any suitable machine including, for example, an electric generator. During operation of such vane pumps, it is important to maintain a fluid-tight seal between the vane and the housing in order to optimize efficiency and maximize power output.
One approach to maintaining the fluid-tight seal between the vane and the housing is to use springs to bias the vane against the housing. Rotary vane pumps that use this approach generally include two or more vanes, and a spring is disposed between the rotor and each vane to bias the respective vane in a radially outward direction and against this housing. The biasing forces exerted by the springs maintain the vanes in continuous contact with the housing through a full 360 degrees of rotation of the rotor within the open chamber of the housing.
Another approach to maintaining the fluid-tight seal between the vane and the housing is to provide open chamber with a non-circular shape. The rotor is centered within the non-circular shaped open chamber, and a vane extends through the rotor to engage at either end with an inner wall of the non-circularly shaped open chamber. The noncircular shape of the open chamber guides the vane through a reciprocating motion back and forth across the rotor to maintain both ends of the vane in contact with the inner wall to establish the fluid tight seals.